The invention concerns a connector for a microcircuit card reader apparatus.
In the context of the invention, "card" means all cards incorporating a hybrid or monolithic integrated circuit or "chip". The term "microcircuit" will be used for this hereinafter. They are, for example, cards in the "credit card" format also called "memory cards". The microcircuit of the card usually comprises a microprocessor or a microcontroller including memory circuits, for example of the "PROM" type. This type of card is designed to be inserted into special devices for reading and/or writing data. For simplicity, these devices are called "readers" hereinafter, although they can naturally write data and assure other ancillary functions (electrical power supply, testing, etc) referred to hereinafter. The data is stored in the aforementioned memory circuits, generally in encrypted form. It is therefore read from memory locations or written to memory locations.
Other logical architectures are used, especially for "electronic purse" or similar applications.
In all cases there are input-output members consisting of contact areas, also called "pads", flush with the surface of one of the main faces of the card. Various standards (ISO, AFNOR, etc) define the position of these contact areas. They are used not only for the aforementioned data inputs-outputs but also for supplying electrical power to the microcircuit and for carrying out various checks, depending on the application concerned (presence test, etc). The reader includes brush contacts that make galvanic contact with the aforementioned areas when the card is correctly inserted into a connector provided for this purpose.
Various trends are currently emerging, including:
the need to improve the security of card reader apparatus; PA1 the trend to miniaturization and therefore to thinner card readers; and PA1 the proliferation of microcircuit card applications plus a rapid fall in connector prices, in direct proportion to the expansion of the corresponding market. PA1 1. The microcircuit of the card must be powered up only if the brush contacts are correctly positioned on the contact areas of the card. Powering up when incorrectly positioned not only prevents operation of the reader system but can damage the electronic circuits of the microcircuit. PA1 2. In particular, the brushes for the data signals must be in position before the power supply voltage is applied to the microcircuit. PA1 3. The user may withdraw the card during processing (this is known as "pull-out"). It is then necessary for the reader to react very quickly to cut off the power supply before the brushes reach prohibited positions (i.e. positions that are hazardous to the integrity of the circuits of the microcircuit). PA1 4. The use of any non-standard object, for example an electrically conductive plate or a faked card, for whatever reason, whether by accident or in the case of attempted fraud, can also cause faults. PA1 The system must operate with all the types of microcircuit with which commercially available cards are equipped, at least for a given application (bank cards, etc). However, the variety of microcircuits is too great to allow a single simple procedure. PA1 Detection occurs on passing between a prohibited area and an operating area. Obviously, in the event of "pull-out", the system must react very quickly. The appropriate electronics is complex and therefore costly. PA1 1. Only the "signal brush" type contact members of the reader must imperatively be in the correct position before power-up via the "power supply brush" and "ground brush" type contact members; PA1 2. The electrical power supply system is always adapted to withstand a short-circuit, if only to deal with the insertion of electrically conductive unauthorized objects (a metal plate, for example). There is therefore no danger if only the brushes which make the connection to the power supply voltage or to ground are in an offset position when the power supply voltage is present. PA1 a connector having a body supporting brush contact members adapted to come into electrical contact with conductive areas associated with said microcircuit of the card when the latter is inserted in the connector; and PA1 an integrated circuit including means for monitoring insertion of the card into the reader and withdrawal of the card from the reader, said circuit being connected to at least some of said brush contact members and to the electronic circuit of the card reader. PA1 short-circuiting of said brush member at the particular potential and said brush member at the ground potential; or PA1 particular variation of said second potential by an amount reaching a particular threshold.
Consequently, a number of problems have to be solved simultaneously, including:
In all these cases it is necessary to disable the reader and to cut off the electrical power supply to limit the risk of damage to the circuits and/or attempts at fraud.
There are many reader systems aimed at reducing some or all of these problems. They can be classified into three major categories.
The first category comprises electronic detector systems.
In systems of this type, an electrical test is carried out before applying an electrical voltage to the microcircuit, for example by measuring the resistance between the brush contacts. If these tests do not yield expected values within a given range the card has been inserted correctly or a foreign body has been inserted in its place.
This type of system has various drawbacks, including:
The second category comprises so-called "landing" systems. One example of a system of this kind is described in French patent application FR-A-2 628 901.
In these systems, the card is positioned against an abutment before it comes into contact with the brushes. Contact is made by relative displacement of the card towards the brushes perpendicularly to the surface of the card (main faces).
Security can be assured only by correct operation of the mechanical parts of the system. However, the latter can be backed up by an "end of travel" contact which disables the power up sequence if the card is not in the correct position. A power up sequence can be established by the height of the brushes or by initializing the following:
Based on these findings, the aim of the invention is to provide a solution to the problems mentioned above whilst alleviating the drawbacks of the prior art systems, some of which have just been described in outline.
Document EP-A-0 139 593 discloses apparatus for reading microcircuit cards including: